OIL AND NATURAL GAS PROPERTIES - Summary of oil and natural gas property costs (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Oil and natural gas properties:
Proved	$ 478,569	$ 358,858
Unproved	109,590	169,863
Total oil and natural gas properties	588,159	528,721
Accumulated depletion, depreciation, amortization and impairment	(359,304)	(98,342)
Oil and natural gas properties, net	228,855	$ 430,379
Unproved leasehold costs	109,590
Aging of Capitalized Exploratory Well Costs, Period One
Oil and natural gas properties:
Unproved	1,643
Unproved leasehold costs	1,643
Aging of Capitalized Exploratory Well Costs, Period Two
Oil and natural gas properties:
Unproved	85,598
Unproved leasehold costs	85,598
Aging of Capitalized Exploratory Well Costs, Period Three
Oil and natural gas properties:
Unproved	22,349
Unproved leasehold costs	$ 22,349

The capitalized costs incurred (excluded from amortization), as of the date of the balance sheet, to purchase, lease or otherwise acquire an unproved property, including costs of lease bonuses and options to purchase or lease properties, the portion of costs applicable to minerals when land including mineral rights is purchased in fee, brokers' fees, recording fees, legal costs, and other costs incurred in acquiring properties.

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Amount of accumulated depreciation, depletion and amortization of oil and gas property carried under the successful effort method. Oil and gas property include, but not limited to, the entity's wells and related equipment and facilities.

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Oil and Gas properties, gross, carried under the successful effort method.

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Oil and Gas properties with proved reserves under the successful effort method.

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